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wampus19 10-11-2013 01:14 AM

95 4.0 random starting problems
Ok I got a 95 4.0 automatic sometimes it cranks and runs perfect but randomly it will crank and run really ruff if I turn it off and keep trying eventually it will crank and run perfect put a new distributor wires plugs rotor button cap and a tps

first jeep

CMike357 10-11-2013 11:12 AM

Is it throwing any codes? When it runs rough is a cold or warm engine?

wampus19 10-11-2013 12:05 PM

It does it hot or cold just randomly had a tps code fixed had a map code but it went away of course the ac code

W5KVV 10-12-2013 01:43 AM

Does it only do it only at startup or does it happen driving down the road? Crank sensor & a roasted o2 sensor come to mind.

I had a 91 XJ that had the same symptoms & it was the crank sensor. Turned out to be a pinched wire in the CPS harness.

wampus19 10-12-2013 10:12 AM

Only at start up it drives perfect

W5KVV 10-13-2013 02:38 AM

OK, that has o2 sensor written all over it. The o2 heater is active until the exhaust gets up to operating temp. If the heater in the o2 sensor is bad, it will cause them to do all kinds of crazy stuff.

CMike357 10-13-2013 09:16 AM

When it starts and runs rough, does giving it more gas help? I'm thinking it may be injector related. Do you ever run a can of cleaner through it?

wampus19 10-13-2013 11:26 AM

No giving it gas won't help you just have to turn it off until it cranks right I already changed the cps I'll check the o2

CMike357 10-13-2013 03:16 PM

I would go ahead and check the MAP sensor. While you're at it go ahead and check the O2 sensor. Try disconnecting the battery to reset the computer.

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